1.1 Purpose and significance:

The automobile suspension is one of themost important assemblies on the modern vehicles. It connects the body and thewheel flexibly. Its main task is to transfer all forces and moments actingbetween the wheel and the body; to mitigate the impact load transmitted to thebody by the road surface and to attenuate the vibration of the bearing systemcaused thereby, to ensure the smooth running of the car; to ensure that thewheel is uneven on the road surface and When the load changes, it has idealsports characteristics to ensure the stability of the car, so that the car canget high-speed driving ability.

At present, customers have higherrequirements on the safety and comfort of vehicles. Traditional passivesuspension structures can hardly satisfy those requirements for ride performance.Since the 1990s, the design of semi-active suspension and active suspension hasgradually emerged. The semi-active suspension and active suspension not onlyovercome the problems of balancing stability and ride performance intraditional passive suspension, but also adapt to various driving conditionsand arbitrary road excitations, becoming an important trend in the futuredevelopment of vehicle suspension. But during the coming period, threedifferent types of suspensions, including passive suspensions, will coexist.

First, the passive suspension is atraditional mechanical structure with non-adjustable stiffness and damping.According to the theory of random vibration, it can only guarantee good resultsunder specific road conditions. Because of its mature theory basis, simplestructure, reliable performance, low cost etc., there is still a certainresearch value at this stage.

Second, the research of semi-activesuspension mainly focuses on two aspects: the study of implementation strategyand the study of actuators. At present, the main development direction of theadjustable damping shock absorber is to change the damping coefficient of theoil damper to change the damping coefficient, and has the characteristics ofsimple structure, low cost and no noise impact.

Third, active suspension researchmainly focuses on reliability and actuators. Because active suspensions containmore sensors, single-chip microcomputers and circuits. For it contains morecomponents, reliability is reduced. Actuator research has focused on usingelectric actuators for replacing hydraulic actuators.

The design of the universal carsuspension system, especially the choice of the type of suspension and thekinematics design of the suspension, has an important influence on the vehicle’shandling stability, ride performance and braking safety. Therefore, thesuspension design can be considered as one of the most important parts in thevehicle design process. Although the current automobile suspension system hasgradually entered the era of active suspension, the suspension basic structuraldesign, K-C characteristic analysis and kinematics simulation verification arestill the most basic and important part of suspension design.

1.2Domestic and foreign research status

At present, for passive suspension, themain research directions, both domestic and abroad, are suspension KCcharacteristic analysis and calculation, optimization of independent suspensionkinematics characteristics and optimization of suspension structure.

Yang Kai analyzed the impact mechanismof the roll center on the track changes, suspension lift, and roll stiffness,and proposed a vehicle roll center setting method with balancing handling and rideperformance in forward development based on the principle of axiomatic design.